Project Summary/Abstract Alzheimer's disease (AD) is a fatal neurodegenerative disease with a global prevalence close to 50 million people, which is expected to double by 2040. Finding an effective treatment for AD has proven difficult, as evidenced by numerous high profile Phase 3 clinical trial failures, most of which directly target the reduction of -amyloid. Thus, it is becoming increasingly urgent to develop new pharmacological strategies to combat AD. Drugs are twice as likely to successfully negotiate the drug development pipeline and obtain FDA approval when their targets are supported from human genetic studies of disease. Human genetic studies have revealed a critical role for microglia involvement in Alzheimer?s disease progression, and it has recently been discovered that the transcription factor PU.1 is a driver of the pro-neurodegenerative phenotype adopted by microglia during aging and disease. This proposal therefore aims to develop novel, newly-discovered PU.1 Inhibitory Modulators (PIMs) for preclinical development, with the long term goal of clinically testing the hypothesis that reducing PU.1 activity in microglia will safely delay the age of AD onset (AAO) in at-risk populations. The studies in this proposal leverage the interdisciplinary structure of the Neurodegeneration Consortium, a unique collaboration between basic science researchers and industry drug development veterans operating under a collaborative agreement to push forward novel therapeutics aimed at treating Alzheimer?s diseaes and other neurodegenerative diseases. Under Specific Aim 1, the in vivo safety and efficacy of PIMs will be determined in mouse models of AD. Under Specific Aim 2, parallel target engagement studies will be performed to identify the target of PIMs, and the identified targets will be used to develop assays to determine the efficacy of PIMs in AD and in ex vivo models. Under Specific Aim 3, selected PIMs will be optimized using PK/PD and ADMET screening to develop lead tool compounds into candidate compounds suitable for future Phase I studies. The combined biology, chemistry, and pharmacology expertise in the Neurodegeneration Consortium, spanning The University of Texas MD Anderson Cancer Center, the Massachussets Institute of Technology, and the Mt. Sinai School of Medicine, make this group of researchers ideally suited to execute the proposed aims.